Telephone calls are sometimes forwarded from one telephone to another. For example, when a user leaves his or her office to work in a computer laboratory, the user might forward his or her office telephone to a telephone in the computer laboratory. The user thereby specifies ahead-of-time that any future call directed to his or her office telephone should be redirected to the telephone in the computer laboratory (i.e., a call directed to the office telephone will cause the computer laboratory telephone to “ring,” while the office telephone will not ring).
As another example, when the user receives a call on his or her office telephone, he or she might wish to transfer the call to another telephone (e.g., a secretary's telephone, etc.) while the call is in progress. Alternatively, the user might wish to include another party in the conversation by bridging the call to an appropriate telephone; this is also known as conference calling.
Forwarding is also commonly employed for email. In particular, a forwarding mechanism is established (e.g., creating a forward file in a UNIX-based system, etc.) so that future email messages addressed to a first address are automatically forwarded to a second address.